Automotive fuel tank electrical fitting

ABSTRACT

A glass-sealed electrical fitting for an automotive fuel tank is mounted on a flange which supports an internal fuel pump and fuel level sensor within the fuel tank. In one form, the glass seal surrounds a plurality of pins longitudinally disposed within an elongated housing which penetrates a fuel tank wall. An outer surface of the housing engages rigidly to the flange, and an inner surface of the housing engages to the glass seal. In another form each pin is sealed to a housing by a separate glass seal.

FIELD OF THE INVENTION

The present invention relates to an automotive fuel tank electricalfitting, and more particularly to a glass-sealed electrical fitting foran automotive fuel tank.

BACKGROUND OF THE INVENTION

It is not unusual to mount fuel pumps inside a fuel tank for automotivevehicles. The fuel pump is typically part of a fuel dispensing unitwhich includes a fuel level sensor, a fuel filter and a structuralmember such as a flange mounted sealably to a fuel tank. Duringassembly, the fuel pump and level sensor are inserted through an openingin the fuel tank as one assembled unit, and the flange is engagedsealably to an exterior side of the fuel tank. An elastomeric O-ringprovides the seal between the flange and the fuel tank. Electrical powertypically routes to the internal devices within the fuel tank (pump andsensor) through an electrical fitting mounted to the flange.

Stringent government environmental regulations are persuading theautomotive industry to make a closer study of fuel vapor permeationthrough a fuel tank. In many instances, the once popular, light weight,plastic fuel tank is being replaced with impermeable steel tanks. Asidefrom the walls of a plastic fuel tank, another source of permeation isthrough the electrical fitting which penetrates the flange. A multitudeof wires electrically connect to the internal devices of the fuel tank;therefore, a corresponding multiple of terminal pins penetrate theflange. Each pin penetration is a potential source for vapor leakage.Existing electrical fittings do not provide a hermetic seal, but userubberized seals or elastic grommets to minimize permeation. However,temperature variations and aging degrade the integrity of the seals,resulting in a loss of the permeation barrier.

SUMMARY OF THE INVENTION

Accordingly, the present invention is a glass-sealed electrical fittingfor an automotive fuel tank. The fitting has a plurality of pins whichpenetrate a wall of the fuel tank and thereby provide the electricalconnections for a fuel pump, fuel level sensor, etc. located inside thefuel tank. A glass seal hermetically engages the metallic surfaces ofthe pins and a metallic surface interconnected to the fuel tank wall.Preferably, the metallic surface interconnected to the fuel tank wall isan inner surface of a housing which surrounds and extends longitudinallyof the pins. An outer surface of the housing engages an inner edge of aflange which mounts to a circumferential edge of the opening of the fueltank.

Objects, features and advantages of the invention include theelimination of fuel vapor permeation through an electrical fitting of anautomotive fuel tank, a permeation barrier capable of withstandingenvironmental temperature fluctuations and aging, and an electricalfitting which is rugged, durable, of economical manufacture and assemblyand in service has a long useful life.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the invention willbe apparent from the following detailed description of the preferredembodiments and best modes, appended claims and accompanying drawings inwhich:

FIG. 1 is a perspective view of a vehicle with a fuel tank having anelectrical fitting according to a preferred embodiment of the presentinvention;

FIG. 2 is an exploded perspective view of the electrical fitting;

FIG. 3 is a top view of the electrical fitting;

FIG. 4 is a cross sectional view of the electrical fitting taken alongline 4—4 of FIG. 3;

FIG. 5 is an exploded perspective view of a second embodiment of theelectrical fitting;

FIG. 6 is a top view of the second embodiment of the electrical fitting;

FIG. 7 is a cross-sectional view of the electrical fitting taken alongline 7—7 of FIG. 6; and

FIG. 8 is a cross-sectional view of a third embodiment of the electricalfitting.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in more detail to the drawings, FIG. 1 shows a vehicle 10having a fuel tank 12 mounted in the rear. An electric fuel pump 14 ismounted within the fuel tank 12 and delivers excess fuel to an engine 16some of which returns to the tank via a pair of supply and return fuellines 18. A battery 22 powers both the fuel pump 14 and a fuel levelsensor 20 mounted inside the fuel tank 12. The electrical power istransferred via a plurality of electrical wires 24. The fuel lines 18and the wires 24 commonly enter the fuel tank 12 through a fuel tankflange portion 26. The flange portion 26 commonly supports, usually in asuspended fashion, both the fuel pump 14 and the fuel level sensor 20.More specifically, the wires 24 electrically communicate through theflange portion 26 via an electrical fitting 28 of the present inventionwhich is mounted on and penetrates through the flange portion 26. Thefuel pump 14, the fuel level sensor 20, the flange portion 26 and theelectrical fitting 28 preferably comprise a fuel sender module 29 whichis manufactured separate from the fuel tank 12.

Referring to FIG. 2, the flange portion 26 becomes an integral part of afuel tank wall 30 of the fuel tank 12 after fitting the fuel sendermodule 29 to the fuel tank 12. A substantial portion of the fuel sendermodule 29 inserts through an opening 32 of the fuel tank wall 30 whichis defined by a circumferential edge 34. Engaging the circumferentialedge 34, or an outward surface of the tank wall 30 about edge 34, is aperipheral edge or lip 36 of the flange portion 26. An o-ring 38 iscompressed sealably between the flange portion 26 and the fuel tank wall30 providing a vapor proof seal or barrier. Any variety of vaporbarriers other than an o-ring may also be applied, including gaskets andsealants. Furthermore, the flange portion 26 can be a unitary part ofthe fuel tank wall 30 thereby alleviating the need for a vapor sealaltogether. However, if the flange portion 26 is unitary to the fueltank wall 30, the fuel sender module 29 is no longer manufacturedseparately from the fuel tank 12.

The flange portion 26 is penetrated by the pair of fuel lines 18 and theelectrical fitting 28. The electrical fitting 28 transverses through ahole 40 of the flange portion 26. The hole 40 is defined by an inneredge 42. A tubular housing 44 of the electrical fitting 28 has an outersurface 46 which engages the inner edge 42 of the flange 26. Housing 44is substantially perpendicular to the flange 26. The outer surface 46and the inner edge 42 of the flange portion 26 form a seam 48, shown inFIG. 4. The seam 48 is preferably a brazed, soldered, or welded jointpreventing vapor permeation through the seam. The housing 44 and theflange portion 26 are metallic, preferably stainless steel or steel.

A plurality of elongated pins 54 are preferably circumferentially spacedapart and parallel to the axis of the housing 44 and extendlongitudinally within the elongated housing 44. A glass seal 52, when ina molten state, is formed about the pins 54 inside the housing 44. Thepins 54 are substantially perpendicular to the glass seal 52. Whensolidified, the glass seal 52 is in a compressed state and prevents fuelvapor permeation through the electrical fitting 28 by engaging ametallic inner surface 50 of the housing 44 and a metallic surface ofthe pins 54. The solidification of the glass to the metallic surfacesalso provides a chemical bond. For the glass seal 52 to achieve ormaintain a compressive state, the thermal expansion rate of the flangeportion 26 and the tubular housing 44 is greater than the thermalexpansion rate of the glass seal 52. Because the plurality of pins 54electrically engage the respective plurality of wires 24, the sealrequires electrical insulating properties which the glass seal 52provides. Furthermore, the glass material must be capable of resistingthermal transients without breaking the bond to either the housing 44 orthe pins 54. Preferable glass materials are barium alkali, borosilicateor soda lime.

Referring to FIGS. 3 and 4 the transverse separation of the pins 54 fromone another and the separation of the pins 54 from the housing 44 willhave an impact on the exposure of the electrical fitting 28 to thermalstresses during temperature fluctuations. To ensure vapor barrierintegrity is not breached as a result of thermal stress, the diameter 56of each pin 54 is preferably equal to or less than the transversedistance or separation 58 between adjacent pins. Furthermore, aperimeter-edge-to-pin transverse minimum distance 60, measured generallyfrom the inner surface 50 of the housing to the pin 54 surface, ispreferably equal to or greater than the diameter 56 of the pin 54. Tominimize the amount of glass material required and to provide easyexternal connector or plug locking capability to the housing 44, thehousing 44 preferably has a circumferential recess 61 which protrudesradially inward and aligns axially with the glass seal 52.

The housing 44 has an outward or top portion 62 disposed above the glassseal 52 and an inward or bottom portion 64 disposed below the glass seal52. The outward portion 62 has an axially extending elongated nubbin 66which mates with a terminal plug end of the electrical wires 24 (notshown). Nubbin 66 assures that the pins 54 are not damaged by improperinsertion of the terminal plug. The plug engages the plurality of pins54 and preferably snaps in place via a plurality of orifices or holes 68which penetrate the outward and inward portions 62, 64 of the housing 44on either axial side of the recess 61. A similar plug engages the inwardportion 64 of the housing 44 to electrically connect the fuel pump 14and fuel level sensor 20.

The plurality of pins 54 commonly comprise four to five pins. The firstpin is a hot lead for the fuel pump 14 and a second pin is the ground. Athird pin provides the hot lead for the fuel sensor 20 and a fourth pinprovides the ground. If the fuel pump 14 is of a variable speed type, afifth pin is needed. Essentially, the electrical fitting 28 may containany number of pins 54 depending upon the electrical devices and requiredelectrical loads contained within the fuel tank 12.

FIGS. 5-7 illustrate a second embodiment of the present invention with aseparate glass seal 252 of each pin. Each one of the plurality of pins254 correspond to and penetrate each respective one of the plurality ofglass seals 252. An aperture plate or tray 244 has a plurality ofcollars 245, each defining an aperture 247 for a glass seal 252 whichengages and seals between its associated collar 245 and pin 254. Thetray 244 has a shoulder or rise 249 with a peripheral edge 246 similarto the outer surface 46 of the housing 44. The peripheral edge 246 andthe inner edge 42 of the flange portion 26′ form a seam 248. As in thefirst embodiment, seam 248 is formed and sealed by welding, soldering orbrazing. Preferably, the collars 245 extend outward or upward from thefuel tank 12. The shoulder 249 is disposed about and extends outwardalong the periphery of tray 244. Preferably, the shoulder 249 terminatesat the peripheral edge 246.

Referring to FIGS. 6 and 7, the spacing of the pins 254, seals 252, andtray 244 are relevant to prevent stress cracking within the seal 252 orbond separation from the pins 254 or the collars 245. The outer diameter257 of each seal 252 preferably is substantially at least two and onehalf times greater than the diameter 256 of the pin. The transverseseparation 259 between adjacent collars preferably is substantially atleast as great as the seal outer diameter 257. The transverse minimumdistance 261 between the inner surface of the shoulder 249 and eachcollar 245 preferably is substantially at least as large as the outsidediameter 257 of the seal. Each seal 252 has an axial length 263 which ispreferably substantially equal to the seal outer diameter 257.

FIG. 8 illustrates a third embodiment of the present invention which issimilar to the second embodiment except that the tray 244 is omitted andthe plurality of collars 345 of the third embodiment are formed directlyin the flange 326. Therefore, the flange 326 no longer contains the hole40 of the flange 26 or the inner edge 42 of the flange 26′ of the firstand second embodiments.

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. It is not intendedherein to mention all the possible embodiments of the invention whichwill be apparent to those skilled in the art. It is understood that theterms used herein are merely descriptive rather than limiting, in thatvarious changes may be made without departing from the spirit or scopeof this invention as defined by the following claims.

1. A sealed electrical fitting for a vehicle fuel tank comprising: ametal wall of the fuel tank having at least one opening through the wallwith a circumferentially continuous edge; at least two elongateelectrically conductive metal pins extending through the at least oneopening and each of the pins having a diameter and a longitudinal lengthgreater than the diameter; at least one seal of glass received in the atleast one opening and bonded to at least one of the pins; adjacentsurfaces of adjacent pins being spaced apart a distance equal to orgreater than the diameter of the pin, the minimum spacing between aperipheral edge of the glass seal and each immediately adjacent pinbeing at least equal to the diameter of the pin, the coefficient ofthermal expansion of the metal wall being greater than the coefficientof thermal expansion of the glass of the glass seal, the metal wall andthe glass seal being configured so that the glass is in a compressedstate, and the same glass seal is bonded to at least two of the pins andthe edge of the same opening through the metal wall.
 2. The electricalfitting of claim 1 wherein the circumferentially continuous edge of theopening has an axial length at least equal to the diameter of the pinand the glass seal has an axial length at least equal to the diameter ofthe pin.
 3. A sealed electrical fitting for a vehicle fuel tankcomprising: a metal wall of the fuel tank having a metal flange, a metaltubular housing fixed to the flange, extending through the flange, anddefining an opening through the wall; at least two elongate electricallyconductive metal pins extending through the opening and each of the pinshaving a diameter and a longitudinal length greater than the diameter; aseal of glass received in the opening and bonded to the pins; adjacentsurfaces of adjacent pins being spaced apart a distance equal to orgreater than the diameter of the pin, the minimum spacing between aperipheral edge of the glass seal and each immediately adjacent pinbeing at least equal to the diameter of the pin, the coefficient ofthermal expansion of the metal wall being greater than the coefficientof thermal expansion of the glass of the glass seal, the metal wall andthe glass seal being configured so that the glass is in a compressedstate; and all of the pins are received in the housing and the glassseal is bonded to all of the pins and the housing.
 4. The electricalfitting of claim 3 wherein the axial length of the glass seal issubstantially equal to the diameter of the pin.
 5. The electricalfitting of claim 3 wherein a circumferential edge of the opening has anaxial length at least equal to the diameter of the pin and the glassseal has an axial length at least equal to the diameter of the pin.
 6. Asealed electrical fitting for a vehicle fuel tank comprising: a metalwall of the fuel tank having a metal flange, at least two metal collarscarried by the flange and each defining a through opening having aninner circumferentially continuous edge; an electrically conductivemetal pin extending through each of the openings and each of the pinshaving a diameter and a longitudinal length greater than the diameter; aseal of glass received in each of the openings and bonded to theassociated pin received therein and the inner edge of the collar inwhich the pin is received; and adjacent surfaces of adjacent pins beingspaced apart a distance equal to or greater than the diameter of thepin, the minimum spacing between a peripheral edge of the glass seal andeach immediately adjacent pin being at least equal to the diameter ofthe pin, the coefficient of thermal expansion of the metal wall beinggreater than the coefficient of thermal expansion of the glass of theglass seal, and the metal wall and the glass seal being configured sothat the glass of each seal is in a compressed state.
 7. The electricalfitting of claim 6 wherein the inner edge of each collar has an axiallength at least equal to the diameter of the pin received therein andthe axial length of the seal received in the collar is at least equal tothe diameter of its associated pin.
 8. The electrical fitting of claim 6wherein the collars are homogeneously integral with the flange.
 9. Theelectrical fitting of claim 6 wherein the wall also comprises a metaltray having a circumferentially continuous outer peripheral edge, thecollars are homogeneously integral with the tray, the flange has anotherthrough opening defined by a circumferentially continuous edge whichbears on the outer peripheral edge of the tray and these mating edgesare fixed and sealed together by one of welding, soldering and brazing.10. The electrical fitting of claim 6 wherein each seal is an annularring with an outside diameter of at least two and one-half times thediameter of its associated pin.
 11. The electrical fitting of claim 10wherein the spacing between immediately adjacent seals is at least equalto the outside diameter of the pins.
 12. A sealed electrical fitting fora vehicle fuel tank, comprising: a metal body having at least oneopening; at least two elongate electrically conductive metal pinsextending through the at least one opening and each of the pins having adiameter and a longitudinal length greater than the diameter; at leastone seal of glass received in the at least one opening and bonded to atleast one of the pins; adjacent surfaces of adjacent pins being spacedapart a distance equal to or greater than the diameter of the pin, theminimum spacing between a peripheral edge of the glass seal and eachimmediately adjacent pin being at least equal to the diameter of thepin, the coefficient of thermal expansion of the metal body beinggreater than the coefficient of thermal expansion of the glass of theglass seal, the metal body and the glass seal being configured so thatthe glass is in a compressed state, and the same glass seal is bonded toat least two of the pins and the edge of the same opening through themetal body.
 13. The electrical fitting of claim 12 wherein thecircumferentially continuous edge of the opening has an axial length atleast equal to the diameter of the pin and the glass seal has an axiallength at least equal to the diameter of the pin.
 14. A sealedelectrical fitting for a vehicle fuel tank, comprising: a metal flange,a metal tubular housing fixed to the flange, extending through theflange, and defining an opening; at least two elongate electricallyconductive metal pins extending through the opening and each of the pinshaving a diameter and a longitudinal length greater than the diameter; aseal of glass received in the opening and bonded to the pins; adjacentsurfaces of adjacent pins being spaced apart a distance equal to orgreater than the diameter of the pin, the minimum spacing between aperipheral edge of the glass seal and each immediately adjacent pinbeing at least equal to the diameter of the pin, the coefficient ofthermal expansion of the housing being greater than the coefficient ofthermal expansion of the glass of the glass seal, the housing and theglass seal being configured so that the glass is in a compressed state;and all of the pins are received in the housing and the glass seal isbonded to all of the pins and the housing.
 15. The electrical fitting ofclaim 14 wherein the axial length of the glass seal is substantiallyequal to the diameter of the pin.
 16. The electrical fitting of claim 14wherein a circumferential edge of the opening has an axial length atleast equal to the diameter of the pin and the glass seal has an axiallength at least equal to the diameter of the pin.
 17. A sealedelectrical fitting for a vehicle fuel tank, comprising: a metal flange,at least two metal collars carried by the flange and each defining athrough opening having an inner circumferentially continuous edge; anelectrically conductive metal pin extending through each of the openingsand each of the pins having a diameter and a longitudinal length greaterthan the diameter; a seal of glass received in each of the openings andbonded to the associated pin received therein and the inner edge of thecollar in which the pin is received; and adjacent surfaces of adjacentpins being spaced apart a distance equal to or greater than the diameterof the pin, the minimum spacing between a peripheral edge of the glassseal and each immediately adjacent pin being at least equal to thediameter of the pin, the coefficient of thermal expansion of the metalcollars being greater than the coefficient of thermal expansion of theglass of the glass seal, and the metal collars and the glass seal beingconfigured so that the glass of each seal is in a compressed state. 18.The electrical fitting of claim 17 wherein the inner edge of each collarhas an axial length at least equal to the diameter of the pin receivedtherein and the axial length of the seal received in the collar is atleast equal to the diameter of its associated pin.
 19. The electricalfitting of claim 17 wherein the collars are homogeneously integral withthe flange.
 20. The electrical fitting of claim 17 which also comprisesa metal tray having a circumferentially continuous outer peripheraledge, the collars are homogeneously integral with the tray, and theflange has a through opening defined by a circumferentially continuousedge which bears on the outer peripheral edge of the tray and thesemating edges are fixed and sealed together by one of welding, solderingand brazing.
 21. The electrical fitting of claim 17 wherein each seal isan annular ring with an outside diameter of at least two and one-halftimes the diameter of its associated pin.
 22. The electrical fitting ofclaim 21 wherein the spacing between immediately adjacent seals is atleast equal to the outside diameter of the pins.